JP3980975B2 - Tire pressure drop alarm method and apparatus, and threshold value change program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a tire pressure drop warning method and apparatus, and a threshold value changing program. More specifically, the present invention relates to a tire pressure drop warning method and apparatus, and a threshold value change program, which can detect tire pressure reduction and issue a warning to a driver.
[0002]
[Prior art]
Conventionally, there is a tire pressure drop warning system (DWS) that detects tire pressure reduction from rotation (wheel speed) information of four wheels. This system uses the principle that, when the tire is depressurized, the outer diameter (the dynamic load radius of the tire) is smaller than that of a tire having a normal inner pressure, so that the rotation speed and the rotation angular speed are increased compared to other normal tires. For example, in the method of detecting a decrease in internal pressure from the relative difference in the rotational angular velocity of the tire, as the determination value DEL,
DEL = {(F1 + F4) / 2− (F2 + F3) / 2} / {(F1 + F2 + F3 + F4) / 4} × 100 (%)
(See Patent Document 1). Here, F1 to F4 are rotational angular velocities of the front left tire, the front right tire, the rear left tire, and the rear right tire, respectively.
[0003]
This DEL value is calculated, and further corrections such as cornering correction and unnecessary data are rejected. When the preset threshold value is exceeded, it is determined that tire decompression has occurred, and the driver is alerted. Has been issued.
[0004]
Also, by extracting the resonance frequency of the vibration frequency based on the wheel speed pulse of the wheel and comparing the decrease deviation based on this resonance frequency with a predetermined deviation, the tire pressure drop that detects the tire pressure state and issues an alarm There is an alarm device (see Patent Document 2).
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 63-305011 [Patent Document 2]
Japanese Patent Laid-Open No. 5-133831 [0006]
[Problems to be solved by the invention]
In the method for detecting a decrease in internal pressure from the relative difference in the rotational angular velocity of the tire, the threshold value is specific to the tire, and even if the tire type, particularly summer tire, winter tire, and puncture, it travels quickly. It is necessary to select according to possible run-flat tires.
[0007]
However, in the current tuning, the threshold value needs to be fixed, and even if the standard tire is replaced with the studless tire, it is necessary to warn, so it is set to an intermediate value between the summer tire and the winter tire. . For this reason, there is a possibility that malfunctions such as false alarms or no alarm or delay even if the pressure is reduced.
[0008]
On the other hand, in a device that detects the state of tire air pressure based on the resonance frequency of the vibration frequency and issues an alarm, for example, when both the studless tire and the run-flat tire are decompressed by 30%, the frequency characteristics of the studless tire greatly change. On the other hand, the frequency characteristics of run-flat tires do not change much. For this reason, when the threshold value is fixed as described above, problems such as false alarms occur.
[0009]
SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a tire pressure drop alarm method and apparatus, and a threshold value change program, which can prevent false alarms and improve the accuracy of determination of air pressure drop. .
[0010]
[Means for Solving the Problems]
The tire pressure drop warning method of the present invention is a tire pressure drop warning method for detecting a decrease in internal pressure of a tire mounted on a vehicle and issuing an alarm, the step of detecting rotation information of each tire, The step of storing the rotation information, the step of displaying the summer tire, the winter tire and the run-flat tire, and the size and type of the currently mounted tire are designated from the displayed tires, and the tire is matched with the tire. The step of switching to the threshold value for determining the internal pressure drop, and at least one of the vertical and front-rear resonance frequencies under the vehicle spring corresponding to the tire size and type, and a decrease deviation based on the resonance frequency And a step of comparing the threshold value, a step of determining a decrease in tire internal pressure using the threshold value, and an alarm based on the determination of the determination means. Characterized in that it comprises a that step.
[0011]
Further, the tire pressure drop warning device of the present invention is a tire pressure drop warning device that detects an internal pressure drop of a tire mounted on a vehicle and issues an alarm, and a rotation information detection means for detecting rotation information of each tire, The rotation information storage means for storing the rotation information of each tire, the type display means for displaying summer tires, winter tires and run-flat tires, and the tires displayed on the type display means are currently mounted. Threshold changing means that designates the tire size and type and switches to the threshold value for determining the internal pressure drop suitable for the tire, and the vertical and longitudinal resonances in the unsprung state of the vehicle corresponding to the tire size and type Means for extracting at least one of the frequencies and comparing the threshold value with a decrease deviation based on the resonance frequency, and a tire using the threshold value Judging means for judging decrease in internal pressure, characterized by comprising a warning means for issuing an alarm based on the determination of the determination means.
[0012]
Further, the threshold value changing program of the present invention is a type for displaying a summer tire, a winter tire and a run flat tire in order to change a threshold value used for determining a decrease in tire air pressure so as to match the tire type. A threshold value changing means for designating a type and size of a currently installed tire from among the tires displayed on the display means and the type display means and switching to a threshold value for determining an internal pressure drop suitable for the tire; Extracting at least one of the vertical and longitudinal resonance frequencies under the unsprung state of the vehicle corresponding to the type and size of the tire, and functioning as a means for comparing the drop deviation based on the resonance frequency with the threshold value It is characterized by that.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a tire pressure drop warning device and method according to the present invention will be described with reference to the accompanying drawings.
[0014]
As shown in FIG. 1, the tire pressure drop warning device includes four FL, FR, RL, and RR (hereinafter collectively referred to as Wi.) Provided in a four-wheel vehicle, where i = 1 to 4, 1: Front left tire, 2: front right tire, 3: rear left tire, 4: rear right tire) and detects whether or not the air pressure is lowered, and issues an alarm, and is provided in association with each tire Wi. The normal rotation information detecting means 1 is provided.
[0015]
As the rotation information detecting means 1, a wheel speed pulse (detection signal) is measured using an electromagnetic pickup or the like, and a power is generated using rotation like a wheel speed sensor or dynamo for detecting rotation information. An angular velocity sensor including one that measures wheel speed pulses can be used. The output of the rotation information detecting means 1 is given to a control unit 2 which is a computer such as ABS. The control unit 2 includes a liquid crystal display element for informing the tire Wi whose air pressure has decreased, a display 3 composed of a plasma display element or a CRT, an initialization switch 4 that can be operated by a driver, and an alarm 5. It is connected.
[0016]
As shown in FIG. 2, the control unit 2 stores an I / O interface 2a necessary for signal exchange with an external device, a CPU 2b functioning as a center of arithmetic processing, and a control operation program for the CPU 2b. The ROM 2c and the RAM 2d into which data is temporarily written or the written data is read when the CPU 2b performs a control operation.
[0017]
Based on the wheel speed pulse output from the rotation information detecting means 1, the CPU 2b calculates the rotation angular velocity F _i of each tire Wi every predetermined sampling period ΔT (sec), for example, ΔT = 1 second. Then, the wheel speed is calculated from the rotational angular speed F _i of each tire Wi. Based on the rotation information of the wheel speed, a decrease in the internal pressure of the tire can be detected as in the conventional case.
[0018]
The wheel speed pulse output from the rotation information detecting means 1 includes a tire vibration frequency component. Therefore, when the wheel speed pulse is subjected to frequency analysis, the resonance frequency in the vertical direction under the spring of the vehicle and A frequency characteristic showing two peak values of the resonance frequency in the front-rear direction can be obtained. Therefore, by detecting at least one of the resonance frequencies in the vertical direction and the front-rear direction under the spring of this vehicle, and detecting a decrease in the internal pressure of the tire by comparing a decrease deviation based on the resonance frequency with a predetermined deviation. You can also. When such an apparatus is used, if the tire size is specified, the resonance frequency can be specified, so that a highly accurate DWS system can be obtained.
[0019]
A method and apparatus for detecting a decrease in tire internal pressure based on wheel speed information will be described below.
[0020]
In the present embodiment, the warning threshold value of the DWS software is switched by the driver specifying the type of tire that is currently mounted using a touch panel or the like. For example, when changing from a summer tire to a winter tire, a screen that allows the user to select a tire on the touch panel is prepared, and the threshold value suitable for the winter tire is selected by the driver. As a result, it is possible to prevent false alarms and improve the accuracy of determination of a decrease in air pressure. Examples of the tire include summer tires, winter tires, and run-flat tires that can run urgently even after puncture.
[0021]
In the tire pressure drop alarm device according to the present embodiment, rotation information detection means 1 for detecting rotation information of each tire, rotation information storage means for storing rotation information of each tire, summer tire, winter tire, The type display means for displaying the run-flat tire, and the tire that is currently mounted is designated from the tires displayed on the type display means, and the threshold is switched to the threshold value for determining the internal pressure drop that matches the tire. A value changing means, a judging means for judging a decrease in the internal pressure of the tire using the threshold value, and an alarm device 5 as a warning means for issuing a warning based on the judgment of the judging means are provided.
[0022]
Then, the threshold value changing program according to the present embodiment sets the control unit 2 from the type display means for displaying summer tires, winter tires, and run-flat tires, and from the tires displayed on the type display means. The designated tire is designated, and it is made to function as a threshold value changing means for switching to a threshold value for determining an internal pressure drop suitable for the tire.
[0023]
As the determination means, a determination value (DEL) for detecting a decrease in tire air pressure can be used, for example, that compares the difference between two diagonal sums of a front tire and a rear tire. This is done by subtracting the sum of the signals from the other pair of wheels on the diagonal from the sum of the signals from the pair of wheels on the diagonal, and as the ratio of the result to the average of the two sums: (1).
DEL = {(V1 + V4) / 2− (V2 + V3) / 2} / {(V1 + V2 + V3 + V4) / 4} × 100 (%) (1)
[0024]
In general, a winter tire is a tire whose tread pattern or material has been changed so that it can run on a snowy road. For example, “SNOW”, “M + S”, “STUDLESS”, “ALL WEATHER” It is a tire with a display such as “ALL SEASON”.
[0025]
Unlike winter tires, summer tires are tires that do not have such indications on the sidewalls.
[0026]
In addition, the difference between summer and winter tires includes tires with different tread pattern stiffness. That is, a tire having a large pattern rigidity that affects vehicle control and the accuracy of detecting the internal pressure of the tire is a summer tire, and a tire having a small pattern rigidity is a winter tire.
[0027]
Examples of the run flat tire include a de novo type run flat tire, an N type run flat tire, and a double structure type run flat tire.
[0028]
Next, the operation of the tire pressure drop alarm device according to the present embodiment will be described with reference to FIGS. First, when the touch panel 6 of the navigation device connected to the tire pressure drop alarm device is turned on, “This system is an alarm system that effectively detects punctures” is displayed on the display screen (step S1). This display screen returns to the previous screen when the return key is pressed, and advances to the next screen when the OK key is pressed. Next, in response to the question “Please input the tire size” from the screen, the currently installed tire size is input using the numeric keypad 7 (step S2). Next, a general tire (summer tire), a studless tire or a run-flat tire is selected as the type of tire, and the key 1, key 2 or key 3 is pressed (step S3). At this time, in order to store the normal state in the computer, after confirming that the tire size and the tire pressure are normal, the initialization switch is pushed (step S4). Thereby, it is determined whether or not the tire size is a compatible size (for example, if 195 / 60R15 is a standard, a tire size such as 205 / 50R16, 185 / 70R14 or the like whose radius does not change) (step S12). If it is determined that the size is not compatible, a warning is issued because there is a malfunction such as a speedometer. If it is determined that the size is compatible, the process proceeds to the next step. At the same time, after the message “Initialization varies depending on the driving conditions, it takes about 15 minutes to 2 hours” is displayed on the display screen (step S5), then the tire pressure is replenished and the tires replaced. If this is the case, attention is urged to redo the initialization work (step S6).
[0029]
On the other hand, in the alarm device, it is determined whether or not the tire to be mounted is a run-flat tire (step S13). If it is determined that the tire is a run-flat tire, a threshold for the run-flat tire is adopted, and tuning is started (step S14). If it is determined that the tire is not a run-flat tire, it is determined whether it is a studless tire (step S15). If it is determined that the tire is not a studless tire, a general tire threshold value is adopted and tuning is started (step S16). On the other hand, if it is determined that the tire is a studless tire, the threshold for the studless tire is adopted, and tuning is started (step S17).
[0030]
The car navigation device detects a travel point using a GPS (Global Positioning System) antenna, etc., and inputs map data of the surrounding area from a CD-ROM or the like to the car navigator body to display a map. The routine information is displayed on a display panel or the like by a routine process, and road information is received from an external transmitter such as a beacon or FM transmitter installed on the road via a beacon antenna. It is possible to use a display panel with road information added thereto by the display routine processing. When this car navigation device is used, a display panel whose screen can be switched can be used as the display.
[0031]
Next, the present invention will be described based on examples, but the present invention is not limited to such examples.
[0032]
Three tire tires (tire size: 195 / 60R15 SP10), winter tire studless tire (tire size: 185 / 70R14 DS1) and run-flat tire (tire size: 205 / 50R16) were prepared as example tires. The tire pressure of the vehicle on which each tire was mounted was set to normal air pressure (1.96 × 10 ⁴ Pa) for the front left tire, front right tire and rear right tire, and 25% decompression for the rear left tire.
[0033]
The run-flat tire is a tubeless tire, and, as shown in FIG. 6, a carcass C having a radial structure extending from the tread portion T to the beat core BC of the bead portion B through the sidewall portions S on both sides. It is a so-called side-reinforcing run flat having a hard rubber reinforcing layer G inside the side wall.
[0034]
Next, as in the case of the conventional example, an intermediate value between the threshold value for the summer tire determination value and the threshold value for the winter tire determination value was recognized, and then a running test was performed. As an intermediate value in this embodiment, D = 0.997 is used. The determination value was calculated based on the above-described equation (1). As a result, as shown in FIG. 7, in the summer tire TSP, the time until the alarm was issued was 11 seconds, in the studless tire TDS, 22 seconds, and in the run flat tire, 8.4 seconds. .
[0035]
Next, threshold values D1 (0.9948), D2 (0.9976) and (0.992) D3 for summer tire TSP, studless tire TDS and run flat tire T are set, and the same running test is performed. As a result, the alarm device of the vehicle equipped with the summer tire TSP, the studless tire TDS, and the run-flat tire T issued an alarm at substantially the same time (15 seconds).
[0036]
As a result, after switching to the threshold value for determining the internal pressure drop suitable for the tire, it is possible to make a more accurate pressure reduction determination by eliminating the false alarm by determining the tire pressure drop using the threshold value. I understand that I can do it.
[0037]
【The invention's effect】
As explained above, according to the present invention, the driver operates the touch panel to identify the currently installed tire, so that the threshold value suitable for the tire can be appropriately switched, so there is no false alarm, and more A highly accurate decompression determination can be made.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a tire pressure drop alarm device according to the present invention.
FIG. 2 is a block diagram showing an electrical configuration of the tire pressure drop alarm device in FIG. 1;
FIG. 3 is a diagram illustrating an example of a touch panel of a navigation device.
FIG. 4 is a flowchart for explaining the operation of the tire pressure drop alarm device.
FIG. 5 is a flowchart of threshold value change.
FIG. 6 is a schematic cross-sectional view of a run flat tire used in Examples.
FIG. 7 is a diagram illustrating a relationship between a determination value and time.
[Explanation of symbols]
1 Rotation information detection means 2 Control unit 3 Display 4 Initialization switch 5 Alarm 6 Touch panel 7 Numeric keypad

Claims (3)

A tire pressure drop alarm method for detecting a decrease in internal pressure of a tire mounted on a vehicle and issuing an alarm, the step of detecting rotation information of each tire, the step of storing rotation information of each tire, and a summer tire The winter tires and the run-flat tires are displayed, and from among the displayed tires , the size and type of the currently mounted tire are designated, and the internal pressure drop determination threshold value suitable for the tire is switched. A step of extracting at least one of up-down and front-rear resonance frequencies in the unsprung direction of the vehicle corresponding to the tire size and type, and comparing the threshold value with a decrease deviation based on the resonance frequency; , A method for determining a decrease in internal pressure of a tire using the threshold value, and a method for alarming a decrease in tire air pressure including a step of issuing an alarm based on the determination by the determination means . A tire pressure drop alarm device for detecting a decrease in internal pressure of a tire mounted on a vehicle and issuing an alarm, a rotation information detecting means for detecting rotation information of each tire, and rotation information for storing rotation information of each tire A storage means, a type display means for displaying summer tires, winter tires and run-flat tires, and the size and type of the currently installed tire among the tires displayed on the type display means are designated, and the tire Threshold value changing means for switching to an internal pressure drop determination threshold value suitable for the vehicle, and extracting at least one of the resonance frequency in the vertical direction and the longitudinal direction in the unsprung state of the vehicle corresponding to the tire size and type, A means for comparing a decrease deviation based on a resonance frequency with the threshold; a determination means for determining a decrease in tire internal pressure using the threshold; and Tire deflation warning device comprising a warning means for issuing an alarm based on the determination of the. In order to change the threshold used to determine the tire pressure drop to match the type of tire, the computer displays a type display means for displaying summer tires, winter tires and run-flat tires. Threshold changing means that designates the type and size of the currently installed tire from among the tires and switches to the threshold value for determining the internal pressure drop that matches the tire, and the vehicle corresponding to the type and size of the tire A threshold value changing program for extracting at least one of up-down direction and front-rear direction resonance frequencies under the spring and functioning as means for comparing the threshold value with a decrease deviation based on the resonance frequency.

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